Further delay in completion of Ohma plant

Japan Electric Power Development Corp (J-Power) has announced a further two-year delay in construction of additional safety measures at unit 1 of the Ohma nuclear power plant, being built in Japan's Aomori prefecture. Construction of the unit is now expected to be completed in late 2023 or early 2024.

Work to build the 1383 MWe Advanced Boiling Water Reactor was about 40% complete in March 2011 when a tsunami caused the accident at the Fukushima Daiichi plant. Construction of Ohma 1 was suspended following the accident, but was resumed in October 2012. At that time, J-Power said it would strive to establish a safe power plant by, among other things, ensuring reinforced safety measures are implemented that take into account the lessons learned from the Fukushima accident.

In December 2014, J-Power submitted an application to the Nuclear Regulation Authority (NRA) to make changes to Ohma 1's reactor installation to strengthen the unit's protection. These measures - including tsunami countermeasures, ensuring power supplies, ensuring heat removal functions, and severe accident responses - were originally expected to be completed by the end of 2020.

However, in September 2015, the company announced a one-year delay in the start of safety equipment construction, pushing back the start of operation to around 2021. This delay was attributed to the prolonged screening process by the NRA after the company was requested to submit additional information about its plans.

On 9 September, J-Power said it expects a further delay of around two years in the completion of the NRA's review and approval process for Ohma 1. It now expects construction of the safety upgrades to begin in 2018 and to be completed in the second half of fiscal year 2023.

J-Power noted, however, "It is still undecided about the operation start time."

The company plans to use all mixed oxide (MOX) uranium and plutonium nuclear fuel in the reactor core of Ohma 1. It would be the first Japanese reactor built to run solely on MOX fuel incorporating recycled plutonium. It will be able to consume a quarter of all domestically-produced MOX fuel and hence make a major contribution to Japan's "pluthermal" policy of recycling plutonium recovered from used fuel. This policy increases Japan's self-sufficiency in energy fuels from 4% to 18% by making maximum use of imported uranium.

The start of construction of the Ohma plant was originally due in August 2007, with commercial operation planned for March 2012. However, the imposition of more stringent seismic regulations put back the start of construction to May 2008 and commercial operation to November 2014.

Researched and written
by World Nuclear News